Tape bias and crosstalk

[fgonza2]

Hi, i wanted to know if there is a link between bias levels and crosstalk and track width. If i bias a tape machine for +6 or +9 is it an issue if i am doing 16 tracks on 1" or 8 tracks on 1/2" ? is the track width too narrow to do that ? I've heard from someone that high bias (above 250nW/m) is only "worthy" if you have a wide track format like 2 track in 1/4" or 24 trk in 2". Is that true ? is there an effect of high bias on adjacent tracks or on narrow tracks ?

thx

 

[jpmorris]

I've not tried it, but intuitively it should do, yes. It's more the record level than the bias signal itself, but if you dump more energy into the tape, the field is going to be wider and more spread out. Have you ever sent a really hot signal to a multitrack and seen it register on the adjacent channels during recording? Increasing the operating level is going to do that on a permanent basis.

For TASCAM, 1/2" 8-track and 1" 16-track actually has the same track width as 2" 24-track, but without the guard bands, so it will indeed be more prone to crosstalk than a 2" machine.

 

[Tim Gillett]

Yes it's not really a bias issue as such. High bias tapes tend to be high energy tapes but that's an indirect correlation.

Crosstalk is generally not a huge issue as with a normal multitrack, the crosstalk is occuring at exactly the same moment across all tracks. Since it's not heard as a separate sound it doesnt stand out much. Any crosstalk gets masked by "itself" on the originating track. Only if you were wanting to completely cut that instrument or voice from the mix might you have some audible crosstalk.

With high energy recordings, usually more of an issue than crosstalk is print through, the pre and post echo on the same track. In my experience, print through can be more of a problem, and the longer the tape is stored, and the higher the storage temperature, the worse it gets.

Again, print through is a problem due to the analog nature of the recording method, which requires capturing a very wide range of frequencies on the one tape track. While there's little or no print through with the high frequencies there is increasingly more print through, the lower the frequency.

Higher energy tapes only made the print through issue worse. In practice, using thicker base tapes, storing tapes "tail out" where possible, conservative recording levels and storage of tapes in a cool environment are good safeguards.

Tim